Modern, tubeless automobile tires are far more reliable and puncture resistant than their tube based predecessors. However, automobile tires are still susceptible to punctures and other damage while driving resulting in a need to change a wheel with a damaged tire on the side of the road. Many motorists do not subscribe to services that offer roadside assistance and must change their own tire. Although most motor vehicles typically come with a lug wrench for removing and reinstalling lug nuts or lug bolts while changing a tire, such lug wrenches are typically manual, have short handles, a fixed head, and provide no indication of the level of torque when tightening a nut or bolt. A short handled lug wrench is compact for easy storage in a trunk or other vehicle compartment, but makes it difficult or impossible for weaker motorists to remove lug nuts because they are unable to obtain enough leverage. A fixed rather than a pivoting head constrains the angle at which the motorist must work. Not having an indication of the level of torque applied can result in a dangerous situation if the motorist is not mechanically inclined and believes they have tightened the lug nuts on a newly installed spare tire to an acceptable torque level when they have not actually done so. Entirely manual wrenches are also not ideal for removing and installing lug nuts because it can take a significant amount of time to completely remove an already loosened lug nut or to initially tighten a lug nut because the manual wrench must typically be removed and repositioned many times. Greater periods of time spent changing a tire by the side of the road increase the chance that the stranded motorist may be struck by another passing vehicle and also may expose the motorist to inclement weather conditions such as extreme cold, rain, snow, sleet, or extreme heat for greater periods of time.
Although not specifically targeted to the specific use of changing the wheels of motor vehicles, various types of torque wrenches are known, including mechanical torque wrenches and electronic torque wrenches that use electronic circuitry for measuring or indicating torque values. For example, U.S. Pat. No. 6,526,853, titled Electromechanical Releasing Torque Wrench, to Jenkins, U.S. Pat. No. 7,234,378, titled Digital Torque Wrench, to Reynertson, Jr., and U.S. Pat. No. 6,981,436, titled Electronic Torque Wrench, to Becker et al., each describe a torque wrench having an electronic torque setting and/or display component. However, all of the torque wrenches described in these patents are manually operated and do not include any type of motorized tightening or loosening capability. Additionally, although U.S. Pat. No. 6,981,436 describes inner and outer telescoping housing portions, these portions appear to be telescopic only in the sense that they are telescopically connected when assembling the wrench or inserting a battery tray. However, that wrench is not described as being usable at multiple lengths. Becker et al. appear to teach away from telescopic operation because the wrench is described as being held together by a single screw that would prevent any elongation or shortening of the wrench.
Various types of powered wrenches are also known, but they generally do not include electronic torque setting, measuring and display devices, are typically tethered to an electrical power cord or pneumatic supply hose, or have other limitations that limit their usefulness in the situations described above. As an example, in U.S. Pat. No. 7,069,816, titled Motor-Driven Screw Driver, Saathoff et al. describe a motor-driven screw driver that includes a torque limiter, but the screw driver includes a fixed rather than a pivoting head, uses separate torque limiters for motorized and manual operation, and makes no mention of the possibility of telescopic operation. Accordingly, there is a need for a cordless motor assisted torque wrench with a pivoting head and other features which would enable a mechanically unsophisticated user to safely change a tire or the like in an adverse environment.